1. Field of the Invention
The present invention relates to an antireflection film composition used for microprocessing in manufacturing process of semiconductor devices etc., and more particularly, to an antireflection film composition used for lithography using a high energy radiation such as KrF excimer laser light (248 nm), ArF excimer laser light (193 nm), F2 laser light (157 nm), electron beam or X-ray as an exposure light source.
2. Description of the Related Art
With a tendency of realizing high integration and high-speed of LSI, a finer pattern rule has been demanded in recent years. The lithography technique with optical exposure, which is used for general purpose at present, is reaching an inherent limiting resolution derived from a wavelength of a light source.
There is widely used optical exposure using g line (436 nm) or i line (365 nm) of a mercury-vapor lamp as a light source for lithography when a resist pattern is formed. It has been considered that a method of using an exposure light with a shorter wavelength is effective as a means for obtaining a further finer pattern. For this reason, for example KrF excimer laser with a shorter wavelength of 248 nm is used as an exposure light source instead of i line (365 nm) for mass-production process of a 64 M bit DRAM processing method. However, a light source with far shorter wavelength is needed to manufacture DRAM with integrity of 1 G or more which needs still finer processing techniques (for example, a processing size is 0.13 μm or less). Accordingly, lithography with ArF excimer laser (193 nm) has been particularly examined.
There is a multilayer-resist process to form a pattern on a substrate with such lithography techniques.
For example, to prevent deterioration of a resist pattern due to halation or a standing wave, a method of providing an Anti-Reflecting Coating between a substrate and a photoresist film is known.
Particularly, to form a pattern with a high aspect ratio on a stepped substrate, a method of using a substrate with an organic film (also referred to as an organic buried film) thereon, a silicon-containing film thereon, and a photoresist film thereon is known (for example, see J. Vac. Sci. Technol., 16(6), November/December 1979).
In view of enhancing resolution, a thinner photoresist film is desirable. On the other hand, in view of obtaining good embedding characteristics for substrate steps and high etching resistance when a substrate is etched, a thicker photoresist film is desirable. Then, three stacked layers can have a layer with good embedding characteristics for substrate steps and high dry etching resistance; and a layer with high resolution, separately. Consequently, it becomes possible to form a pattern with a high aspect ratio on a stepped substrate.
As the silicon-containing film, for example, a silicon-containing antireflection film may be used.
In order to form a pattern on such a substrate, first, the pattern circuit area of a photoresist film is exposed and then developed with a developer to form a resist pattern on the photoresist film. Second, a pattern is formed on an antireflection film by using the photoresist film as a mask. In this way, the resist pattern is transferred sequentially, and finally, a pattern is formed on a substrate.
However, when an antireflection film is formed with an antireflection film composition and a photoresist film is formed thereon, the intermixing phenomenon can conventionally occur in the vicinity of the antireflection film/photoresist film interface. Furthermore, when a resist pattern is formed on the photoresist film on the antireflection film, the resist pattern can have footing profile or undercut profile. The footing profile can generate a dimension conversion difference after the antireflection film is etched. And the undercut profile, also referred to as reverse tapered profile or negative profile, can cause a resist pattern to collapse after development. Moreover, when an antireflection film is formed, its underlying layer can be damaged. Such problems occur particularly in silicon-containing antireflection films.
In conventional hydrocarbon antireflection film compositions, an antireflection film is formed by crosslinking crosslinkable components linked to film-forming materials in the compositions with a thermal acid generator (See Japanese Unexamined Patent Application Publication No. 2003-114533). Such hydrocarbon antireflection films have very dense structures, thus effectively preventing amine components etc. in a photoresist layer from migrating.
However, when an antireflection film is formed with a silicon-containing antireflection film composition and a photoresist film is formed thereon, the antireflection film has a structure where acids diffuse very easily due to property of silicon-oxygen-silicon bond which is a skeleton forming the antireflection film. Therefore, acid generated upon exposure of the photoresist film diffuses into the antireflection film before contributing to the reaction deprotecting protecting groups of alkali-soluble groups in the resist, resulting in footing profile or residue at the time of developing the resist.
Such phenomenon is observed in conventional hydrocarbon antireflection films. And in order to solve such a problem, a method for adding photo acid generators to antireflection films is disclosed, for example, in Japanese Patent Publication No. 3408415, Japanese Unexamined Patent Application Publication No. H07-86127, H05-107769, etc. The Publication No. 3408415 and No. H07-86127 disclose techniques regarding hydrocarbon antireflection films and both of the publications do not refer to silicon-containing antireflection films at all. On the other hand, the Publication No. H05-107769 discloses techniques adding photo acid generators to silicon-containing antireflection films. However, overlying resist of the silicon-containing antireflection films is negative resist, and the Publication No. H05-107769 does not refer to any case using positive resist which is mainly used for forming resist patterns.